1. Field of the invention
This invention relates to a method of chemical surface treatment of copper and its alloys with an acidic aqueous solution of hydrogen peroxide in which hindering action of dissolved chlorine ion in removal of the metals and oxide scales by dissolution is inhibited. More particularly, it is directed to inhibiting the hindering action of dissolved chlorine ion in the chemical surface treatment of copper and its alloys such as the pcikling, etching or chemical polishing for which an acidic aqueous solution of hydrogen peroxide is used by adding to the solution methylcyclohexanol or cyclohexanol or both of the two.
2. Description of the Prior Art
Chemical surface treatments such as pickling which involves dissolving oxide scales on the surface of metallic material for the removal, etching which involves removing a portion of the metal layer by dissolution and chemical polishing which involves glazed treatment of the surface are widely used in industrial fields in which metallic materials are dealt with.
It is known that the acidic aqueous solution of hydrogen peroxide has an excellent dissolving activity as a chemical surface-treating agent for copper and copper-alloy materials. However, when there is incorporated chlorine ion at 1 p.p.m. or more in the solution, the metal- or oxide scale-dissolving activity will be greatly reduced with unsatisfactory finishing of the pickling, etching or chemical polishing resulted. In order to improve the reduction, there is heretofore known a method in which a silver compound such as silver nitrate or sulfate is added to remove the incorporated chlorine ion as precipitates of inactive silver chloride. In the method, however, it is difficult to add the silver ion in an amount equivalent to the chlorine ion. If the silver ion is added in excess, silver will be precipitated upon the surface of copper and its alloys with an disadvantage that dissolution of the metal or oxide scale is undesirably inhibited.